Lecture 18 – Digestive System (Human Anatomy)

Digestive System

Body system responsible for ingestion, motility, secretion, digestion, absorption, and elimination of wastes.

Gastrointestinal (GI) Tract

Continuous muscular tube from oral cavity to anal canal through which food passes.

Accessory Digestive Organs

Tongue, teeth, salivary glands, liver, gallbladder, and pancreas; secrete or aid in digestion but are not part of the GI tube.

Bolus

Moistened mass of ingested food as it enters the GI tract.

Chyme

Semi-fluid mixture of partially digested food leaving the stomach.

Peristalsis

Wave-like contractions that propel bolus/chyme along the GI tract.

Segmentation (Mixing)

Simultaneous contractions that churn contents with digestive secretions without net forward movement.

Parotid Salivary Gland

Largest salivary gland; empties near upper second molar; produces serous saliva.

Sublingual Salivary Gland

Smallest salivary gland; beneath tongue; numerous ducts open to floor of mouth.

Submandibular Salivary Gland

Salivary gland under mandible; produces majority of saliva via single duct.

Salivary Amylase

Enzyme in saliva that initiates carbohydrate digestion.

Lysozyme

Antibacterial enzyme in saliva that helps sterilize food.

Dentition

Collective term for the teeth.

Mastication

Mechanical process of chewing food into smaller fragments.

Incisors

Chisel-shaped anterior teeth adapted for slicing.

Canines

Pointed teeth posterolateral to incisors used for puncturing and tearing.

Premolars

Bicuspid teeth with flat crowns and ridges for crushing and grinding.

Molars

Largest, most posterior teeth specialized for heavy crushing and grinding.

Enamel

Hard, calcium-phosphate